Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> P;
int h,w,cnt;
char c[60][60];
int ans[60][60],flag[60][60];
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
queue<P> que;

int main(){
  cin >> h >> w;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> c[i][j];
      if(c[i][j]=='.') cnt++;
    }
  }
  flag[0][0]=1;
  que.push(P(0,0));
  while(!que.empty()){
    P p=que.front();
    que.pop();
    for(int i=0;i<4;i++){
      int x=p.first+dx[i],y=p.second+dy[i];
      if(0<=x&&x<h&&0<=y&&y<w&&!flag[x][y]&&c[x][y]=='.'){
        flag[x][y]=1;
        ans[x][y]=ans[p.first][p.second]+1;
        que.push(P(x,y));
      }
    }
  }
  cout << (ans[h-1][w-1]?cnt-ans[h-1][w-1]-1:-1) << endl;
}